Field-rheostat.



H. J. WIEGAND.

FIELD RHEOSTAT.

ICATION FILED AUG 2 APPL 2, 1914 I 1,192,360. Patented July 1916.

UNITED STATES PATENT OFFICE.

HENRY J. WIEGAND, 0F MILWAUKEE, WISCONSIN, ASSIGNOB TO THE CUTLER-HAMMER MFG. 00., OF MILWAUKEE, WISCONSIN, A. CORPORATION OF WISCONSIN.

FIELD-RHEOSTAT.

To all whom it may concern:

Be it known that I..HENRY J. VVIEGANi), a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Field-Rheostats, of which the following is a full, clear, concise, and exact description. reference being had tothe accompanying drawing, forming part of this specification.

This invention relates to rheostats and more particularly to such devices of the type known as field regulators.

One of the objects of the invention is to provide a simplified and improved rheostat comprising parts capable of cheap manufacture and ready assembly into compact and durable structure.

Other objects and advantages will appear hereinafter in connection with the description of the preferred embodiment of the invention illustrated in the accompanying drawing, in which,

Figure 1 is a top plan view of a rheostat. Fig. 2 is a side view thereof partially in section, and Fig. 3 is a sectional perspective view of a part thereof showing certain details of construction.

The rheosta-t shown comprises, generally, a flat insulating base 1 having a resistance element 2 connected in sections with contact plates '3 to be engaged by a-movable contact brush 4 for inserting in, or removing from,

the regulated circuit predetermined amounts of resistance.

Referring more specifically to the drawing, the base 1 comprises a flat rectangular piece of suitable non-conducting material, for example, soapstone. The contact plates 3 are mounted about /a circle on the upper face of the base and are accurately positioned thereon by means of downturned lugs 5 at the ends of each contact which fit into complementary recesses provided therefor in the base. Eachof the contacts 3 has also a projecting lug at its outer end reflexed to constitute a hook for connection with the sinuous reflexed resistance wire 2 which is laid on the smooth surface of the base about the outer margin thereof. A layer of cementitious insulation 6 is applied. over the resistance wire and covers also the outer ends of the contact lates. By thus embedding the wire 2 and t e ends of the contacts, both of these elements are thoroughly protected Specification of Letters Patent.

Patented July 25, 1916.

Application filed August 22,1914. Serial No. 858,071.

and firmly maintained on the base against possibility of loosening or damage. It is thus apparent that the stationary parts of the rheostat constitute a structural unit of noteworthy simplicity and manufacturing practicability.

The operating member of the device comprises a rotatable member 7 secured to the base with its axis at the center of the contacts 3 and providedwith a radially pro jecting'arm 8 having a cylindrical brush i spring pressed into engagement with the plates 8. The arm 8 is electricallyconnect ed with one of the terminals 9 at an edge of the base while the other terminal connects with the contact plate 3 on which the brush el: rests during initial position of the operating member. When the rheostat is con nected circuit it will be obvious that the path of the current is from one terminal to the brush 4; and through varying amounts of the resistance 2, in accordance with the position of the operating member, to the opposite terminal.

A circular cover plate 10 of stamped. metal is provided to rest upon the base and additionally shield the conducting parts of the device. This coverhas four marginal lugs or feet 11 spaced for. attachment to the corners of the base 1 and which, when resting thereon, maintain the cover in slightly elevated position above the upper surface of the base. The cover is also provided with a central opening through which the operating member 7 extends. In order to insure thorough ventilation, the cover isprovided with numerous apertures 12 in its upper surface and is mounted, as set forth, with its edge spaced from the surface of the base whereby a free circulation of air is permitted both under and through the cover.

Furthermore if additional ventilation of the rheostat is desired, the cover 10 may be entirely removed without unduly exposing any of the current carrying parts.

A suitable upright pin 13 is fixed to the base adjacent the contact plates 2 and in a position to limit movement of the operating" of the base piece 1 which project clear of the circular area of conducting elements thereon, both the cover supporting lugs 11 and the base supporting, lugs 14 are attached to the base by common bolts 15 without interposed insulation.

It is to be noted that the various elements of the structure described are of a character capable of easy manufacture and assembly and that the device as a whole is compact and sturdy. Although the particular form of structure described has been proven especially advantageous, it is to be understood that ceriain variations and modifications may be made therein without departure from the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is 1. A rheostat having a fiat insulating base, a resistance arranged on the surface thereof, a layer of cementitious material applied to said base to embed said resistance and a series of fiat contact plates restingupon the surface of said base and connected to said resistance, each of said contacts having a part extending beneath said cementitious layer and each having a plurality of anchoring lugs projecting downwardly into said base, one of said lugs being disposed beneath the cementitious layer andthe other at the free end of its respective contact plate.

2. In a device of the character described, in combination, a substantially flat insulating base, a resistance element thereon, contact plates on said base and electrically connected to said resistance element, a cementitious insulating layer embedding said resistance element, and a metallic cover for said base having its margin spaced therefrom for insuringfree ventilation thereunder.

, 3. A rheostat provided with a base, a circuit resistance element mounted upon a face thereof, a controlling element for said resistance pivoted concentrically therewith and a cover for said resistance element having radially disposed lugs for attachment to said base, said cover being spaced from said base for ventilation and having ventilating apertures in the top thereof.

*1. A rheostat having a base and a resistance element thereon, a cementitious insulating layer embedding said resistance element, a metallic cover for said base, and means for attaching said cover to said base at pointsoutside the area of the currentcarrying parts thereon.

5. A rheostat including an insulating base, a resistance mounted thereon, a metallic cover for said resistance having lugs or feet for attachment to said base, separate sup porting lugs or feet for said base, said sets of lugs or feet overlapping and common means securing both sets of said lugs or feet to said base.

6. A rheostat provided with a substantially rectangular base having beveled corners, a circular resistance element mounted thereon, a circular cover for said resistance element having lugs or feet for attachment to said base adjacent to the corners thereof, supporting lugs or feet for said base fitting the beveled corners thereof and overlapping said former lugs or feet and a bolt passing through said base and each pair of overlapping lugs or feet to secure the latter to the former.

In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

HENRY J. WIEGAND. Witnesses L. A. WATSON, TEKLA BAST. 

